1. Field of the Invention
The present disclosure is directed to an apparatus for etching an edge of a wafer, and more particularly, to an apparatus for etching an edge of a wafer, which is constructed to prevent the wafer from being over-etched.
2. Description of the Related Art
There are two methods of etching an edge of a wafer, in which underlying layers are removed along photoresist patterns formed on a wafer: wet etching and dry etching. In a dry etching process, an appropriate gas is injected into a process chamber to induce a plasma, and ionized particles in the plasma are then allowed to collide with the surface of the wafer for removal through physical or chemical reactions.
In a dry etching apparatus, a polymer is generated as an etching byproduct as the result of the reaction between the wafer and the etching gases. Micro-particles of such polymers may be deposited on an edge portion of the wafer and remain thereon.
However, particles remaining on an edge portion of the wafer may cause deterioration of the wafer yield. Therefore, various techniques for removing particles from an edge of a wafer have been proposed.
Existing methods for removing particles from an edge of a wafer include an exposure followed by wet etching, and dry etching using plasma.
When the particles existing on the edge of the wafer are removed by dry etching, plasma may penetrate the chip as well as the edge of the wafer, resulting in over-etching of the wafer.